Hungry planet: Can we produce more food without expanding agricultural land? – Part 1

Productivity gains will reduce both the need for additional land and the emissions caused by production processes. Without large crop and livestock productivity gains, agricultural land requirement will be orders of magnitude greater by 2050, and greenhouse gas (GHG) emissions could double.

In some mitigation analyses, including reports by the Intergovernmental Panel on Climate Change (IPCC), agricultural productivity gains are barely mentioned, for reasons that are unclear. Even under our baseline projection, with its large increases in crop and livestock yields, the World Resources Institute projects that agricultural land will expand by 593 million hectares to meet expected food demand.

Unless projected growth in demand for food can be moderated, to avoid land expansion both crop yields and pasture-raised livestock yields will have to grow even faster between 2010 and 2050 than they grew in previous decades.

Arguments can be made for both pessimism and optimism:

• Studies have projected that farmers could achieve far higher yields than they do today. However, methods for estimating these “yield gaps” tend to exaggerate gap sizes and farmers can rarely achieve more than 80 percent of yield potential. The most comprehensive study suggests that fully closing realistic yield gaps is unlikely to be enough to meet all food needs.
  
• The massive yield gains of the 50 years from 1960 to 2010 were achieved in large part by doubling irrigated area and extending the use of scientifically bred seeds and commercial fertilizer to most of the world. Only limited further expansion of these technologies remains possible.
  
• Optimistically, farmers have so far continued to steadily boost yields by farming smarter in a variety of ways, and new technologies are opening up new potential.
  

Whatever the degree of optimism, the policy implications are the same: going forward, the world needs to make even greater efforts to boost productivity than in the past to achieve a sustainable food future.  

Increasing livestock and pasture productivity

Demand for milk and meat from grazing ruminants (such as cows and sheep) is likely to grow even more than demand for crops. Because pasture makes up two-thirds of all agricultural land, the productivity of livestock will critically affect future land use and emissions.

Large productivity improvements for pork and poultry are unlikely in developed countries because of biological limits. In developing countries, because traditional backyard systems make use of waste and scavenging, shifts to modern systems increase output but do not reduce land-use demands or emissions. By contrast, ruminant systems have greater potential to improve, as suggested by the wide range in productivities across countries.

The GHG emissions that result from producing each kilogram of beef – a good proxy for all aspects of productivity – are far higher in some countries than in others. Land use requirements can be 100 times greater, and the quantity of feed 20 times greater. Higher ruminant productivity can be achieved by increasing output per animal through improved food quality, breeding, and health care; and by increasing feed output per hectare. Neither requires a shift to feedlots. On pastures with good rainfall, productivity can be increased by proper fertilization, growing legumes, rotational grazing, and adding supplemental feeds in dry seasons and during the last few months of “finishing.” In the “cut and carry” systems that predominate in Africa and Asia, farmers can grow a wide variety of improved forage grasses and shrubs with high protein leaves.

The real challenge lies in the scale of improvement required. Because much grazing land is too dry or too sloped to support large feed improvements, almost every hectare of wetter, accessible, and environmentally appropriate land would need to achieve close to its maximum productive potential to meet expected global demand without the need for further land conversion.

• Most ruminant farmers need to shift from low management operations, which take advantage of cheap land, toward careful, intensive grazing and forage management using more labour and inputs.
  
• Governments in developing countries, which are home to the great majority of ruminants, should establish livestock productivity targets and support them with greater financial and technical assistance.
  
• Implementation of systems to analyse improvement potential and track changes in different areas and on different types of farms would help guide these investments and monitor their effects.    
  

Improving crop breeding to boost yields

Breeding of improved crops is generally credited for half of all historical yield gains. Breeding can both increase the potential yield of crops under ideal conditions and help farmers come closer to those potential yields by better coping with environmental constraints. Countries that have invested more in recent years in crop breeding, such as Brazil and China, have seen vast improvements in their yields.

“Incremental” crop breeding has been the primary driver of yield gains through assessment and selection of the best performing existing crops, followed by purification, rebreeding, production, and distribution. In the United States, improved maize varieties are released every three years. Speeding new crop cycles would boost yield growth in many countries such as Kenya and India, where new grain varieties are released typically every 13 to 23 years.

Much debate has focused on genetically modified organisms (GMOs), which involve insertion of genes from one plant into another. The debate has centred overwhelmingly on two types of traits that assist pest control through glyphosate resistance and expression of Bt (Bacillus thuringiensis), a biological pesticide. Some bona fide debate is appropriate about whether the ease of use and relatively lower toxicity provided by these traits in the short term, and their potential value to small farmers without access to pesticides, justifies the longer-term risks of building resistance in weeds, worms, and insects – potentially leading to more pesticide use in the future. There is no evidence that GMOs have directly harmed human health.

Gene editing has far greater potential. Sometimes new genes can provide the only viable mechanisms for crops to survive new diseases. New genes may also play a major role in combating environmental challenges by making crops more efficient at absorbing or suppressing harmful emissions.